Transmission Method and Devices in a Communication System with Contention-Based Data Transmission

ABSTRACT

A method is described for data transmission by user equipments adapted to transmit data using resource blocks allocated by a radio network. The radio network is adapted to allocate resource blocks to a dedicated one of the user equipments or to a plurality of the user equipments. The method comprises the step of allocating at least one of the resource blocks that is not allocated to any dedicated user equipment to a first plurality of the user equipments. The allocation is signaled to the user equipments. A first user equipment of said first plurality obtains data for transmission. At least a first part of the data is transmitted by the first user equipment using said at least one resource block. Devices embodying the invention and methods of operating the devices are also described. Contention based data transmission in uplink is enabled without previous scheduling request and scheduling grant.

TECHNICAL FIELD

The present invention relates to a method for data transmission by userequipment adapted to transmit data using resource blocks allocated by aradio network. Devices embodying the invention and methods of operatingthe devices are also described.

BACKGROUND

In many communication systems, for example in mobile communicationnetworks, a plurality of devices shares resources on a common medium fortransmission. One option of avoiding resource conflicts is to perform ascheduling or allocation of resources to selected devices while otherdevices are not allowed to use the same resources. Dynamic allocation ofthe resources during operation of the communication network cansignificantly increase the transmission efficiency so that the resourcesare not left unused if some of the devices have presently no or only asmall amount of data to transmit while others require more resources.Dynamic allocation is particularly suitable if a single instancecontrolling the allocation is in communication with the plurality ofdevices sharing the medium. An example are user equipments in a cell oranother area of a wireless communication system being controlled by aradio base station or a radio network controller.

Dynamic allocations are simplified if the resources are subdivided intoresource blocks which can be allocated individually or in groups.Depending on the transmission technology, a resource block can forexample be defined by a frequency range and a time interval in which adevice is allowed to transmit data.

One example is the uplink transmission in LTE (Long Term Evolution) ofthe Universal Mobile Telecommunications System which is based onDFT-spread OFDM (Direct Fourier Transform spread Orthogonal FrequencyDivision Multiplexing), often referred to as Single Carrier FrequencyDivision Multiple Access (SC-FDMA). The LTE uplink is divided intoresource blocks in time and frequency dimension as shown in FIG. 1. Inthe time dimension, subframes can be subdivided into two slots each asillustrated by their subdivision in the figure. In the frequencydimension, more than one resource block may be simultaneously allocatedto one user, e.g. to user #2 having 3 allocated resource blocks in theexample. LTE systems use a single carrier property which means thatresource blocks allocated to a user equipment are consecutive in thefrequency dimension.

In LTE, the uplink Resource Blocks (RB) are dedicated to users by meansof uplink scheduling grants (SG) being transmitted on the PhysicalDownlink Control Channel (PDCCH). The uplink grants are addressed to theCell-Radio Network Temporary Identifier (C-RNTI) of the user equipments.More details about this procedure can be found in TechnicalSpecification 3GPP TS 36.321 V8.5.0 (2009-03) of the 3rd GenerationPartnership Project; Technical Specification Group Radio Access Network;Evolved Universal Terrestrial Radio Access (E-UTRA) Medium AccessControl (MAC) protocol specification.

For initiating a transmission, a user equipment (UE) 20 first requestsuplink resources by transmitting a Scheduling Request (SR) 22 asillustrated in FIG. 2. In LTE this can be done using the Physical UplinkControl Channel (PUCCH).

The radio network, e.g. the eNB (Evolved Node B) 24 controlling the cellwhere the user equipment is located, selects the resource blocks to beallocated to the user and can select also the uplink transport format,defining parameters associated with the uplink transmission, like e.g.transport block size, physical layer coding, and modulation.

In this way, the eNB 24 performs uplink link adaptation and is aware ofthe format of the uplink (UL) transmission before it is received. Abenefit of this procedure is that no uplink physical control channel isrequired to carry the information in contrast e.g. to TFCI (TransportFormat Combination Identifier) signaling in WCDMA (Wideband CodeDivision Multiple Access). This reduces the uplink control signaling andimproves coverage. In reply to the SR 22 the radio network representedby the eNB 24 in FIG. 2 sends a scheduling grant (SG) 26 indicating theselected RB. When the UE has received the SG it can start uplink datatransmission 28 on the allocated uplink resources.

Despite the benefits of dynamic allocations as illustrated by the LTEuplink access scheme, there exist drawbacks. The scheduling request andscheduling grant before a transmission increase both the latency andsignaling overhead in the communication system and thus reduce thetransmission efficiency.

SUMMARY

It is an object of the present invention to obviate the abovedisadvantages and propose methods and devices which allow increasing thetransmission efficiency in a communication system with resourceallocation.

According to the invention, the method described in claim 1 isperformed. The invention can also be embodied in devices and methods asdescribed in the other independent claims. Further embodiments arespecified in the dependent claims.

A method is described for data transmission by user equipments adaptedto transmit data using resource blocks allocated by a radio network. Theradio network is adapted to allocate resource blocks to a dedicated oneof the user equipments or to a plurality of the user equipments. Themethod comprises the step of allocating at least one of the resourceblocks that is not allocated to any dedicated user equipment to a firstplurality of the user equipments. The allocation is signaled to the userequipments. A first user equipment of said first plurality obtains datafor transmission. At least a first part of the data is transmitted bythe first user equipment using said at least one resource block.

Furthermore, a control device is described for the allocation ofresource blocks of a radio network to user equipments adapted totransmit data using said resource blocks. The control device comprises aprocessor adapted to allocate one or more resource blocks either to adedicated one of the user equipments or to a plurality of the userequipments. The processor comprises a controller adapted to allocate atleast one of the resource blocks that is not allocated to any dedicateduser equipment to a first plurality of the user equipments. Atransmitter of the control device is adapted to initiate the signalingof the allocations to the user equipments.

The invention can also be embodied in a user equipment adapted totransmit data to a radio network using resource blocks. The userequipment comprises a receiver adapted to receive at least oneallocation of a resource block from the radio network. The at least oneallocation allocates the resource block either to a dedicated userequipment or to a plurality of user equipments. A processor of the userequipment is adapted to process the at least one allocation and todetermine that at least one resource block is allocated to a pluralityof the user equipments comprising said user equipment. A buffer of theuser equipment is adapted for storing data for transmission. The userequipment comprises also a controller for selecting the at least oneresource block responsive to a status of the buffer and the allocationdetermined by the processor. A transmitter of the user equipment isadapted to transmit at least a first part of the data using said atleast one of the resource block selected by the controller.

A method of operating a control device is described for the allocationof resource blocks of a radio network to user equipments adapted totransmit data using said resource blocks. The method comprises the stepof allocating one or more resource blocks either to a dedicated one ofthe user equipments or to a plurality of the user equipments. At leastone of the resource blocks that is not allocated to any dedicated userequipment is allocated to a first plurality of the user equipments. Themethod of operating the control device furthermore comprises initiatingthe signaling of the allocations to the user equipments.

A method of operating a user equipment adapted to transmit data to aradio network using resource blocks comprises the step of receiving atleast one allocation of a resource block from the radio network. The atleast one allocation allocates the resource block either to a dedicateduser equipment or to a plurality of user equipments. In the method, theat least one allocation is processed to determine at least one resourceblock allocated to a plurality of the user equipments comprising saiduser equipment. In reply to data obtained for transmission, at least afirst part of the data is transmitted using said at least one determinedresource block.

The methods can also be embodied as programs which are for examplestored on a data carrier or loadable into the devices, e.g. as asequence of signals.

The foregoing and other objects, features and advantages of the presentinvention will become more apparent in the following detaileddescription of preferred embodiments as illustrated in the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of resource blocks in a wireless communicationsystem;

FIG. 2 shows the initiation of a data transmission in an LTE system;

FIG. 3 shows a flowchart of a method for the initiation of a datatransmission;

FIG. 4 shows an example of a communication system in which the proposedmethod can be used;

FIG. 5 shows a flowchart of an embodiment of the method with respect tothe involved devices;

FIG. 6 shows a data unit for transmission and a resource block;

FIG. 7 shows a flowchart of a data transmission involvingacknowledgements;

FIG. 8 shows a user equipment and a control device;

FIG. 9 shows aspects of a user equipment and a control device adapted tothe proposed method;

FIG. 10 shows contention based uplink resources and transmission;

FIG. 11 shows a comparison of transmission timelines of contention basedand contention free transmission;

FIG. 12 shows an example of contention based transmission forunsynchronized user equipments;

FIG. 13 shows a further example of contention based transmission forunsynchronized user equipments;

FIG. 14 shows a flowchart of user equipment operation;

FIG. 15 shows contention based uplink transmission withacknowledgements.

DETAILED DESCRIPTION

The proposed method as depicted by FIG. 3 relates to data transmissionby user equipments. The user equipments, e.g. terminals like mobiletelephones, smart phones or laptop computers, share a commontransmission medium, for example the air interface if they are locatedwithin a common area or subarea covered by a radio network, e.g. theuser equipments 402, 404 in a cell 412 illustrated in FIG. 4.Accordingly, the radio network preferably allocates transmissionresources on the transmission medium in order to avoid resourceconflicts between the user equipments. The transmission resources can besubdivided into resource blocks. Resource blocks can be defined indifferent ways depending on the transmission technology, e.g. as afrequency interval, a time interval, a spreading code in a Code DivisionMultiple Access system, or any combination of such parameters like afrequency and a time interval as depicted in FIG. 1. Depending on thetransmission technology, the resource blocks may have uniform ordiffering sizes. The user equipments are adapted to transmit data usingresource blocks allocated by the radio network, for example by a controldevice which may be the radio base station or eNB for the cell.

The radio network is adapted to allocate resource blocks either to adedicated one of the user equipments or to a plurality of the userequipments. The plurality can also comprise all user equipments in theradio network. The radio network may leave resource blocks withoutallocation, e.g. in case of low traffic load. It is not required thatall resource blocks available for the radio network are allocated fordata transmission of user equipment. The allocation may be limited e.g.to one or more shared channels or specific channels may be exempt fromthe allocation. For example, control channels or random access channelsmay exist which are permanently assigned to resource blocks and notconsidered for the allocation to single or pluralities of userequipments.

The allocation of resource blocks can be performed on a regular basis ormay be triggered by certain events. For example specified transmissiontime intervals (TTI) may exist in the radio network and the allocationof resources may be performed for each TTI or for groups of intervals.The method according to FIG. 3 generally starts with step 32 ofallocating resource blocks to dedicated user equipments, for example inresponse to scheduling requests from the respective user equipments. Itis possible that no resource blocks are allocated in this step, e.g. ifno user equipment has data for transmission and requested scheduling. Atleast one resource block is not allocated to any dedicated userequipment and can be allocated in step 34 to a first plurality of theuser equipments. It is in principle possible to exchange the sequence ofsteps 32 and 34 although the depicted sequence simplifies it to allocatededicated resources with priority which is often preferable. However,allocations performed in steps 32 and 34 are coordinated, e.g. usingcorresponding checks, so that the at least one resource block is notallocated to any dedicated user equipment. The allocations are thensignaled to the user equipments in step 36, e.g. via a transmitter ofthe radio network and a receiver of the user equipment.

A user equipment of said first plurality obtains data for transmissionin step 38. The data can be received from an internal source within theuser equipment, for example from an application executed in the userequipment. Data can also be received from other devices connected to theuser equipment. The user equipment can perform a check if allocatedresources are available for data transmission. It is also possible thatthe data for transmission is obtained already at an earlier point intime before step 36 and the user equipment waits for reception of asuitable allocation. In step 40, the data or at least a part of the datais transmitted by the user equipment towards the radio network usingsaid at least one resource block, i.e. a transport block comprising atleast a part of the data is sent in the resource block.

Using resources allocated to the first plurality, a user equipment caninitiate a transmission without a prior scheduling request and anaccording grant so that the latency for initiating a transmission can beconsiderably enhanced. Optionally, also the required control signalingcan thus be reduced. Simultaneously existing dedicated resources allowexecuting other data transmissions from the same or another userequipment without contention for these dedicated resources. Improvedtransmission conditions can be provided on the dedicated resources andalso the competition for the resources allocated to the plurality ofterminals can be limited by using dedicated resources.

In contrast to the dedicated resources, the resources used fortransmission in step 40 are allocated to more than one user equipment sothat contention for these resources exists between the user equipmentsfrom the first plurality. Accordingly, such resources and the respectivetransmissions are often denoted as “contention based” in the following.In an embodiment, at least one second user equipment may thus send datain said at least one resource block. In contrast, dedicated resourcesand transmissions using dedicated resources are also named “contentionfree” below and allocated to a single user equipment.

The radio network can be for example a long term evolution (LTE) radionetwork which is illustrated in FIG. 4 together with an evolved packetcore network (EPC) for mobility management and connections to othernetworks. In FIG. 4, continuous lines indicate data connections, brokenlines indicate control signaling and double arrows represent wirelesstransmissions. The EPC comprises one or more mobility managemententities MME 424, a serving gateway 428 and a packet data networkgateway 430 for connecting the EPC to other networks, e.g. to theInternet or Operator Services. The LTE radio network comprises aplurality of evolved nodes B (eNB) 422, 424 which each handleconnections with user equipments 402-410 in one or more cells 412, 414of which only two are shown for clarity. Wireless connections can behanded over between eNBs if the user equipments 402-410 move betweendifferent cells 412, 414. Further elements which may be part of thecommunication system, e.g. routers or further nodes like anauthentication server, are omitted in FIG. 4 for clarity. If the radionetwork is an LTE network, the resource allocations are preferablyperformed in an evolved Node B of the LTE network.

FIGS. 5 and 7 show further flow charts illustrating differentembodiments of the method with respect to the involved devices. The flowcharts illustrate both sequences of steps in a user equipment designatedas UE 1 and in a control device. The different embodiments described inmore detail below can be implemented independently of each other unlesssuch dependence is explicitly indicated.

In initial step 502 of FIG. 5, identifiers are associated with userequipments and pluralities of user equipment. For example, in an LTEsystem allocations are identified by the Cell-Radio Network TemporaryIdentifier. Correspondingly, in an embodiment a specific identifieridentifies the signaled allocation of the at least one resource blockallocated to the first plurality, sometimes also denoted as grant. Inthis way, dedicated resources and resources allocated to a plurality ofdevices can be distinguished by the according identifier which can alsobe associated with a specified coding of information in the respectiveresource blocks. However, it is also possible to change suchassociations dynamically or signal the coding together with anallocation.

If identifiers are used, the user equipment determines the associationof identifiers with itself in step 504, i.e. those identifiers which areassociated with UE 1. The determination can be based on signaling asindicated by the arrow between steps 502 and 504 but may be basedalternatively or in addition on stored values, e.g. if ranges ofidentifiers are permanently attributed to contention based resources. Sothe user equipment UE 1 is both aware of one or more dedicatedidentifiers and one or more identifiers identifying a plurality of userequipments in which it is included and can scan any received allocationsignaling for these identifiers.

As described before, resource blocks are allocated in steps 506 and 508by the control device and grants signaled in step 510 to the userequipments including UE 1. The radio network can signal the grants withthe identifier on a control channel or on a broadcast channel. Theformer option is preferable in case resource allocations to pluralitiesof user equipments frequently change, e.g. on the order of single or fewtransmission time intervals, while the latter option is preferable ifallocations of resources to user pluralities remain constant over longerperiods of time so that occasionally broadcasted allocations aresufficient.

As identifiers are associated with the user equipments the signalingcomprises the allocations identified by the identifiers and the userequipment UE 1 receives the signaling in step 512. The signaledallocations may also comprise a designation of one or more resourceblocks or further information, e.g. a modulation and coding scheme forthe transmission. User equipment UE 1 can then identify in step 514 atleast one resource block or grant which is allocated to a plurality ofuser equipments comprising UE1, i.e. a contention based resource whichUE 1 can use. Step 514 can also comprise determining one or morededicated resource blocks allocated to UE 1. The identification in step514 is based on the association determined in step 504.

When user equipment UE 1 obtains or detects data for transmission instep 516, e.g. data forwarded by an upper protocol layer into a bufferfor transmission, it selects in step 518 one or more resource blocks fortransmission from the resource blocks or grants identified in step 514.It is also possible to select whether any allocated resource block isused as described below, i.e. step 518 of selecting comprises notnecessarily a choice among different resource blocks. If the detecteddata initiates a new transmission the user equipment has in most casesno dedicated resources available. Therefore, selecting a contentionbased resource block allows starting the transmission without the delayfor requesting allocation of a dedicated resource.

Generally, more than one signaled allocation can be available fortransmission by a plurality of users, e.g. simultaneously or atdifferent times. The user equipment can then select the at least oneresource block for transmission based upon at least one parameter of atransport format, comprising e.g. a modulation and coding scheme, one ormore radio conditions, a data priority and an amount of the data fortransmission. The user equipment may thus base the decision on whetherto use a resource block allocated to a plurality of users and whichresource block to use based on present transmission conditions and/oravoid occupying resources which are not required or unsuitable fortransmission, e.g. by using a large resource block for a small amount ofdata in case resource blocks have different sizes. Resources may beselected based on the data priority and thus e.g. reserved for controlsignaling or emergency calls. The signaled allocation can also beassociated with an allowable selection in dependence on the at least oneparameter. In this case, the association in step 502 can optionally alsoassociate the identifiers with corresponding selection parameters. In afurther embodiment, the first plurality of the user equipments comprisesa pre-specified group of user equipments. In this way resources may bereserved for user groups with specific subscriptions by associating thecorresponding groups with different pluralities. Different of thepreceding options may be combined.

In an embodiment, the at least one resource block can also be associatedwith an access probability. The access probability defines theprobability that a resource block is used for transmission by a specificuser equipment from the plurality of user equipments to which theresource block is allocated if the user equipment has available data fortransmission, i.e. the fraction of resource blocks used by a specificuser equipment having data for transmission from the total number ofresource blocks allocated to the user equipment. The user equipment canthen perform a decision on whether to use, the at least one resourceblock for transmission based on the access probability. For example theuser equipment can determine a random value before accessing theresource block and performs only a transmission in the resource block ifthe random value exceeds the threshold wherein the value or thethreshold is a function of the access probability. In this way, loadsteering can be performed and the probability of access collisions canbe adjusted. The decision can be part of selection 518. Accordingly, itis also possible that no resource block is selected for transmission andthus no transmission performed. In such a case the user equipment maysend a request for allocation of a dedicated resource to the controldevice.

Finally the data is transmitted in step 520 in the selected resourceblock or blocks using a corresponding transmitter of the user equipment.Depending on the amount of data received it is possible that only a partof the data is transmitted and the remaining data buffered for latertransmission. Also the sent data may be stored in order to allowretransmissions in case of transmission failures. The data is receivedin step 522 either by the control device or optionally also in anotherdevice as indicated by the broken lines. In embodiments of the method,the received data can contain information which is intended for use infurther resource allocations, e.g. a buffer status report of the userequipment. In this case, the corresponding information is preferablyforwarded to the control device if the receiver of the data is adistinct device.

FIG. 6 shows data for transmission as a protocol data unit (PDU) 602,e.g. as a MAC PDU in an LTE system. The PDU 602 comprises a headersection 604 comprising control information and a data section 606comprising data for transmission. In addition to the informationelements discussed below, e.g. identifier 610 or indication 614, headersection 604 may comprise further information as indicated by the freefield. One option for the transmission of identifier 610 or indication614 is to append them in a subheader at the end of the header section,so that the header size can flexibly be adapted if this informationshall be included but they may also be located at other positions withinthe PDU. For transmission the PDU is forwarded to a physical layer ofthe transmitting device as indicated by the arrow. The physical layermay perform further processing of the data, e.g. coding, interleaving,modulation or adding of data for error detection in a cyclic redundancycheck (CRC), for embedding the content of PDU 602 into a resource block608. The results of the further processing of PDU 602 are indicated bythe dotted parts of resource block 608.

For resources which are allocated to a plurality of user equipments thereceiver of a transmission needs to determine which user equipment sentthe transmission. To solve this ambiguity, the user equipment caninclude identifier 610 into the at least one resource block 608, e.g. byinserting it into the PDU 602. The identifier 610 identifies the userequipment to the radio network. The identifier 610 is preferably uniqueand can be for example an identifier used to identify dedicatedresources allocated to the user equipment. However, other identifiersare possible, e.g. a Temporary Mobile Subscriber Identity (TMSI), oreven a random value provided that the probability is low for having oftwo user equipments with the same identifier in the area for which theallocations are performed.

In a still further embodiment, the user equipment includes at least onereference signal 612 into the at least one resource block, the referencesignal comprising a predefined content for adjusting a decodingprocedure of the resource block by the receiver. The user equipmentmodifies the reference signal 612 in a specified way, e.g. by a specificphase rotation. In this way, transmission from different user equipmentswithin one resource block may be distinguished based on the modificationof the reference signals. In response, the data receiver may adapt thedecoding of the data in the resource blocks or the control device maymodify further allocations, e.g. in order to reduce transmissioncollisions or by associating resource blocks with other transportformats. Modified reference signals can also be used to transmit otherinformation for adjusting a decoding procedure, e.g. the used allocationif different allocations with different associated transmission formatsidentify a single resource block so that the modification of thereference signal comprises the information about the association.

Optionally, the user equipment includes an indication 614 of the amountof data received for transmission into the at least one resource block,e.g. by inserting it into the PDU 602. In this way, further dedicated orcontention based resources may be scheduled to the user equipmentwithout the necessity of further signaling. Alternatively or inaddition, the user equipment can send a scheduling request for anallocation of a dedicated resource block outside the at least oneresource block 608, e.g. in the same, a previous, or a subsequenttransmission time interval. This allows an allocation of resources evenif the transmission in the resource block 608 allocated to the pluralityof user equipments is lost, e.g. due to data collision with another userequipment. Processing logic in the control device performing theallocations can determine the required resources in case both anindication and a scheduling request are received from the same userequipment.

FIG. 7 shows further embodiments of the method in a flow chart whichstarts with a transmission of data in a selected resource block in step702. This can for example be a transmission as discussed in steps 40 or520 of the preceding examples, i.e. the transmission is performed in oneor more contention based resource blocks allocated to a plurality ofuser equipments. The transmission may be totally lost or corrupted asindicated by the explosion symbol at arrow 704 representing thetransmission, e.g. due to radio conditions. Examples are strong signalfading or a collision with data of a simultaneous transmission 706 fromanother user equipment denoted as UE X. In particular in case ofsignificantly differing transmission conditions, e.g. if UE X is locatedclose to the receiver associated with the base station or eNB of thecell while UE 1 is located close to the cell edge, it may happen thattransmission 706 is successfully received in step 708 while transmission704 is corrupted. This corresponds to the example shown in FIG. 7.Depending on the scenario it is of course also possible that bothtransmissions are lost, both successfully received or both received in acorrupted version.

Data received in corrupted transmissions may optionally be stored instep 710 for later soft combining with one or more furthertransmissions. The storing of a corrupted transmission may be subject tofurther conditions which indicate whether the corrupted transmission issuitable for soft combining. For example if the control device detectsindications that the corruption of the data is due to data collision,e.g. if it detects reference symbols with different modificationsindicating different user equipments as data sources, it may decide notto store the corrupted transmission.

In an embodiment, the radio network sends an acknowledgement to the userequipment. The acknowledgement acknowledges the transmission using theat least one resource block, i.e. a successful reception of theinformation in the at least one resource block. This ensures aconfirmation of successful data reception. Optionally, theacknowledgement comprises an identifier of the user equipment. In thisway it is ensured that the user equipment is correctly identified amongthe user equipments which can transmit in a particular resource blockallocated to a plurality of users. In FIG. 7, this is indicated in step712 where the control device sends a confirmation indicating asuccessful reception of data from UE X which is received by userequipment UE 1 in step 714. The acknowledgement can be addressed to thefirst user equipment, e.g. the identifier of the user equipment. It isalso an option to address the acknowledgement using the specificidentifier identifying the signaled allocation. Also in the latter case,the acknowledgement can contain an identifier of the first userequipment

In case acknowledgements are used a loss of the data transmission can beindicated by the events that no acknowledgement is received after aspecified time or that an acknowledgement associated with the at leastone resource block is received which identifies a different userequipment. The user equipment can determine this in step 716, e.g. dueto expiry of a timer in a routine waiting for the acknowledgement or dueto the reception of an acknowledgement indicating a successful receptionof a transmission from UE X for the resource block used. Theacknowledgement can also identify the resource block if more than onecontention based resource block is allocated in an interval of time towhich the acknowledgement in step 714 may correspond. For data that islost during transmission, the user equipment can select a new resourceblock for retransmission in step 718 and perform the retransmission ofthe data in step 720.

The retransmission from UE 1 is received at the control device in step722. If a user equipment performs a first transmission and aretransmission of data, the radio network can combine information fromthe first transmission stored in step 710 and the retransmission if bothtransmissions are received and potentially comprise errors. Inparticular soft combining of one or more retransmissions with theoriginal transmission can be used. In the flow chart, soft combining isindicated as an option in step 724 and can be based on the data storedin step 710 and the retransmission. Step 724 can be omitted if theretransmission is successfully decoded without errors. If the data issuccessfully decoded, either due to a successful retransmission orsuccessful soft combining, an acknowledgement can be sent to UE 1 instep 726. In step 728 the user equipment can then clear any of the sentdata which was still stored for the purpose of retransmissions.

FIG. 8 shows a user equipment 802 in connection over a wireless link 808with a control device 804, e.g. an eNB. The user equipment 802 comprisesa transceiver unit 806 for sending and receiving signals on wirelesslink 808. A processor 810 processes the data received by the transceiverunit and the data to be sent via transceiver unit 806. Data processingfor data transmission is generally performed in a protocol stack with aplurality of layers involved in the transmission, each layer executingspecific tasks in the transmission and providing services to higherlayers. Received data is forwarded and processed stepwise from thelowest layer towards the higher layers while data to be sent isforwarded in the opposite direction. Data processing for sending datamay involve for example any combination of the operations headercompression, ciphering, segmentation, concatenation, multiplexing,coding, interleaving, modulation, etc., the individual operations aswell as the corresponding reverse operations for receiving data beingexecuted in one or more specific layers.

As an example, a physical layer PHY, a MAC layer and an RLC layer areindicated in FIG. 8. One or more further layers may exist as indicatedin broken lines. Data can for example be created and evaluated in anapplication layer of the user equipment 802, e.g. in response to inputand for creating output via input and output devices 812 for a user ofthe equipment, comprising e.g. well-known hardware like microphone,loudspeaker, keyboard, screen and/or touchscreen, camera, interfaces toother devices etc.

Processing of data on both sides of a wireless link 808 is normallycomplementary. Accordingly, the control device 804 has also atransceiver unit 820 and a processor 822 comprising those layers whichare associated with the transmission on the wireless link 808. In theexample these are the layers PHY, MAC, RLC and optionally also one ormore higher layers as indicated in broken lines. Each of these layers isin communication with the respective layer in the user equipment asindicated by the broken arrows. The layers process the data normally asa data packet, also denoted PDU of the respective layer, e.g. a MAC PDUor an RLC PDU, and the sending layer on one side of link 808 may add aheader to the PDU which is then evaluated in the corresponding receivinglayer.

Still higher layers, e.g. the application layer or an IP layer may beterminated in other devices (not shown), e.g. another mobile terminal ora server in the Internet, to which data received over wireless link 808is forwarded via a further connection 824. Control logic 826 and one ormore transceiver units 828 for connections within the radio networkand/or to a core network exchange the data between the protocol stack inprocessor 822 and the further connections.

Processors 810 and 822 may be implemented in one or more processingunits and generally comprise processing logic for executing routines andsoftware as well as memory for storing data. Processing units androutines may also be implemented by specific hardware.

FIG. 9 depicts further aspects of processors 810 and 822 in more detailwhich relate to embodiments of the proposed method. Other items areomitted for clarity, e.g. those already shown in FIG. 8. In the figures,corresponding elements are implemented in the MAC layer. However, itshould be understood that this particular implementation and thepresence of a MAC layer in general is merely an example.

In the user equipment, processor 810 comprises a buffer 902 for storingdata for transmission. The data will generally be stored in the bufferby a higher layer, e.g. the RLC layer, which in turn can receive thedata from still higher layers. A data processing unit 904 retrieves datafrom the buffer and processes it for transmission, e.g. by executingfunctions for one or more of the operations described with respect toFIG. 8. The processed data is forwarded by a forwarding unit 906 to thenext lower layer for transmission, e.g. to the physical layer. Datareceived by the user equipment is forwarded in the opposite direction,i.e. received by forwarding unit 906 and forwarded to the higher layerafter processing in processing unit 904. A plurality of such units mayexist in the processor and they can be dedicated, e.g. to individualconnections, or dedicated units 904, 906 may exist for reception andtransmission.

Processor 810 can further comprise an allocation identification unit 908for determining resource blocks which are allocated to the userequipment. The allocations can for example be read from received PDUsduring the processing in unit 904. The identified allocations can thenbe used by selection unit 910 if data for transmission is detected, e.g.when entering buffer 902 or when being processed in data processing unit904, in order to transmit the data in the allocated resources. Aresource request unit 912 can initiate requests for further resources,in particular if the amount of detected data exceeds the capacity of theallocated resources. Requests initiated by resource request unit 912 canfor example be inserted into the header of a PDU processed or created bydata processing unit 904. It should be noted that the depictedsubdivision of the units is merely an example, their functions could bereplaced by other means and it is e.g. possible to implement allocationidentification unit 908, selection unit 910 and/or resource request unit912 as part of data processing unit 904.

The processor 822 in the control device comprises also a buffer 930, adata processing unit 932 and a forwarding unit 934 as described withrespect to the user equipment although the processing capacity and/ornumber of corresponding units is generally higher if the control deviceis designed for communication with a plurality of user equipmentssimultaneously. Furthermore the control device comprises a resourcecontroller 936 for allocating resources to user equipments andpluralities of user equipments with which the control device isassociated, e.g. if they are located in the area controlled by thecontrol device and/or have performed an attachment procedure towards thecontrol device. One or more memories 938 may store the allocations sothat received resource blocks can be associated with the respective userequipment or plurality of user equipments. A memory can also storeallowable allocations, e.g. if frequency bands can not be used due toother base stations or due to spectrum regulations or if a standardspecifies that specified resource blocks are only available for controlchannels or pluralities of user equipments and not for dedicatedallocations to specific user equipments. A block determination unit 940may determine in response to reports or requests from the user equipmentthat the respective user equipments require allocation of furtherresource blocks and can thus trigger the resource controller 936 toallocate a corresponding amount of dedicated or contention basedresources. Again, the depicted subdivision of the units is merely anexample, their functions could be replaced by other means, and it ispossible to implement the units in different ways or within each other.

If at least two protocol layers are involved in a transmission of thedata, a lower one of the protocol layers may control whether thetransmission is performed in a resource block allocated to a pluralityof user equipments or in a dedicated resource block, e.g. usingselection unit 910. The lower protocol layer can then send a modeindication to a higher one of the protocol layers as indicated byconnections 918, 942 in FIG. 9. The mode indication can indicate whetherthe transmission is performed in a resource block allocated to aplurality of user equipments. Alternatively or in addition, a modeindication can also relate to other parameters of the transmission, e.g.whether retransmissions are supported. In response, the higher protocollayer adapts at least one operating parameter according to the modeindication. For example timers 920, 944 for controlling reordering ofdata packets or polling for status reports may be adapted in the higherprotocol layer. Mode indications can also be sent if the resources orparameters are changed during a transmission of data forwarded by thehigher protocol layer. In the example of LTE, the lower layer can be forexample the MAC layer and the higher layer the Radio Link Control (RLC)layer.

In many cases, transmissions in a radio network are performed inspecified time intervals, e.g. TTIs, and the resource blocks correspondaccordingly to time intervals. In an embodiment, consecutive allocationsto the first plurality of the user equipments are separated by a timeinterval. This allows that also user equipment which is not synchronizedto the radio network can use the allocated resource blocks because datasignals extending in time beyond a resource block do not overlap with aconsecutively assigned resource block due to the separation.

User equipment can optionally also send a preamble for time alignment inassociation with the at least one resource block. In response to thepreamble the radio network can send time alignment information to theuser equipment. The preamble can be sent in the at least one resourceblock allocated to the plurality of user equipments or on a randomaccess channel outside the resource block allocated to the plurality ofusers.

In a further embodiment, a traffic load is determined for the radionetwork or a specific device or subarea, e.g. as an absolute amount ofload like a data or packet rate in an eNB or an output power in a cell,or as a relative amount, e.g. a fraction of allocated resource blocks.It is also possible to determine a number of data collisions duringtransmission for traffic load determination. The step of allocating canthen be performed in dependence on the determined load, e.g. step 506 inFIG. 5. For example the number of resource blocks allocated to aplurality of users may be reduced with increasing load, and e.g. be setto zero above a threshold. In this way data collisions may be reduced.

A communication system can be adapted to any embodiments of the methoddescribed. Typically the method will be performed involving a controldevice in a radio network of the communication system and a plurality ofuser equipments in communication with the control device.

In general terms, a control device embodying the invention is adapted toperform the allocation of resource blocks of a radio network to userequipments which are adapted to transmit data using said resourceblocks. The control device comprises a processor adapted to allocate oneor more resource blocks either to a dedicated one of the user equipmentsor to a plurality of the user equipments. It is possible to allocate allresource blocks in this way or to leave resource blocks withoutallocation, e.g. in case of low traffic load. Allocations can beperformed for example in response to requests received by a receiver ofthe control device and/or due to settings stored in a memory.Furthermore, the processor comprises a controller adapted to allocate atleast one of the resource blocks that is not allocated to any dedicateduser equipment to a first plurality of the user equipments. Atransmitter initiates the signaling of the allocations to the userequipments in response to the allocations. The control device can beadapted to any embodiments of the described method. It can be forexample implemented in the radio base station or eNB of an LTE radionetwork.

Described as a method of operating a control device of a radio network,the control device allocates one or more resource blocks either to adedicated one of user equipments or to a plurality of the userequipments. The user equipments are adapted to transmit data using saidresource blocks. At least one of the resource blocks that is notallocated to any dedicated user equipment is allocated to a firstplurality of the user equipments. The control device initiates thesignaling of the allocations to the user equipments, for example usingan associated transmitter.

In an embodiment, the processor is adapted to determine a number ofresource blocks required for transmission of the data from the userequipment, for example based on a buffer status report or a schedulingrequest from the user equipment received over a receiver, e.g.transceiver unit 820. In response, the processor can allocate one ormore dedicated resource blocks to user equipment based on the determinednumber. This allows a fast allocation of the required transmissionresources. An embodiment of this option can be implemented for exampleusing block determination unit 940.

The invention can furthermore be embodied in a user equipment adapted totransmit data to a radio network using resource blocks. The userequipment comprises a receiver adapted to receive allocations ofresource blocks from the radio network. The or at least one of thereceived allocations allocate the resource blocks either to a dedicateduser equipment or to a plurality of user equipments. A processor of theuser equipment processes the allocations and determines that at leastone of the resource blocks is allocated to a plurality of the userequipments which comprises said user equipment.

The user equipment comprises furthermore a buffer or another memory forstoring data for transmission. The data can for example be received froman application executed in the user equipment. A controller which may beimplemented in the processor, e.g. selection unit 910 of FIG. 9, selectsthe at least one resource block responsive to a status of the buffer,e.g. when data for transmission is detected, and the allocationdetermined by the processor, i.e. when it is detected that the resourceblock can be used by a plurality of user equipments comprising thepresent user equipment. The data is then forwarded to a transmitter,e.g. using a physical layer of the user equipment, and at least a firstpart of the data is transmitted using said at least one of the resourceblock selected by the controller.

In terms of a method of operation, a user equipment adapted to transmitdata to a radio network using resource blocks receives allocations ofresource blocks from the radio network. The or at least one of theallocations allocate the resource blocks either to a dedicated userequipment or to a plurality of user equipments. The user equipmentprocesses the allocations to determine at least one of the resourceblocks allocated to a plurality of the user equipments comprising saiduser equipment. When it obtains data for transmission the user equipmenttransmits at least a first part of the data using said at least onedetermined resource block.

The user equipment can comprise a routine, e.g. in the processor, tocheck whether a dedicated resource block is allocated to the userequipment. In this case the controller can select the at least oneresource block based on said check. As an example the user equipment mayonly be allowed to transmit data on a resource block allocated to theplurality of equipments if it does not have a dedicated resourceavailable. It may also be allowed to transmit only initial data of atransmission on resource blocks allocated to the plurality ofequipments, e.g. for a limited period of time, while furthertransmissions must be performed on dedicated resources. In this way theprobability of data collisions can be reduced. Adherence to such rulescan be ensured by the checking routine in cooperation with thecontroller. An embodiment of this option can be implemented for exampleusing checking routine 914 in selection unit 910 of FIG. 9.

In an embodiment, the user equipment can comprise a further checkingroutine, e.g. in the processor, adapted to perform a check whether atleast one resource block is allocated to a plurality of user equipments.It can then trigger the sending of a scheduling request to the radionetwork based on said check. In particular the user equipment may detectthat no resources blocks are allocated to any plurality in which it iscomprised. In this way, the radio network can control that the userequipment sends data only on dedicated resources by omitting allocationsof resource blocks to pluralities of user equipments, for example incase of high load or frequent data collisions on resources attributed topluralities. An embodiment of this option can be implemented for exampleusing checking routine 916 in selection unit 910 of FIG. 9.

In a still further embodiment, the user equipment comprises a routine,e.g. in the controller, to determine a number of resource blocksrequired for transmission of the data and to initiate a request to theradio network for the allocation of a dedicated resource block based onthe number. Correspondingly, small amounts of data or the initial partof data can be transmitted in resources attributed to the pluralitywhile larger amounts of data can be sent on dedicated resources. Thiscan improve both the signaling overhead for the data transmission andthe probability of data collisions on contention based resources. Anembodiment of this option is illustrated by resource request unit 912 ofFIG. 9.

In the following, the proposed methods and devices are furtherelaborated with specific reference to LTE systems and more particularlywith respect to the uplink in LTE, i.e. for the link from the UE towardsthe radio network. However, it is obvious to a skilled person thatcorresponding concepts could also be applied in other communicationsystems. As outlined before, a basic concept is that user equipments(UEs) are allowed to use uplink resource blocks in a contention basedfashion that have not been allocated to a dedicated user, and would thusotherwise be left unused. In this way, the resources for contentionbased access do not affect other scheduled uplink transmissions.

A general property of Contention Based (CB) transmissions is that theerror rate increases if data packets collide with each other. Collisionsreduce the transmission throughput and the throughput becomes sensitiveto the system load. If the load is allowed to increase beyond a certainlimit, the collision probability increases rapidly, the system becomesunstable, and the throughput decreases. Therefore, CB transmissionspreferably do not interfere with Contention Free (CF) transmissions,i.e. each allocated resource block is preferably either allocated to CBor CF transmission only. One way to achieve such isolation is to allowCB transmission only in uplink resource blocks that have not beenreserved for CF uplink transmission.

Identification of CB Resource Blocks and Available CB Configuration

An example for the division of the uplink resources into CB anddedicated CF resource blocks is depicted in FIG. 10. FIG. 10 showsresource blocks for transmission in both the downlink (left part of thefigure) and uplink (right part), e.g. of a cell controlled by an eNB.Resource blocks are limited in the frequency domain (horizontal axis)and correspond in the examples of FIG. 10—and of FIGS. 12, 13 and 15 towhich the following descriptions of the resource blocks apply also—invertical direction to one transmission time interval each correspondingto the vertical subdivisions of the figures. While the figures showuplink and downlink simultaneously it should be understood that thepresent invention may be also implemented in a Time Division Duplex(TDD) mode of a communication system in which uplink and downlink aretime-multiplexed in the same frequency band.

Dedicated CF resources are marked with horizontal and vertical gridhatching and free or idle resources with upward diagonal hatching. CBresources are marked with diagonal tiling and are further subdivided inthree groups marked a, b and c, indicating that in this example threedifferent shares of CB resource are allocated. For each share of CBresource, a CB-RNTI (Contention Based Radio Network TemporaryIdentifier) is defined. The CB-RNTI is used on the Physical DownlinkControl Channel PDCCH to identify the CB resource grants. The availableCB-RNTIs in a cell can be either broadcasted in the cell (to be used forinitial access), signaled to each user using dedicated RRC (RadioResource Control) signaling, e.g. during RRC connection setup, or usingan RRC reconfiguration message. The CB-RNTIs may also be specified(hard-coded) in the standard.

At both outer edges of the uplink in FIG. 10 the resource blocks arereserved for control information, e.g. the PUCCH. The control channelsare indicated by vertical hatching. In particular, they compriseresource blocks which have a downward diagonal hatching in the figuresand in which bits are reserved for scheduling requests SR from theindividual user equipments.

Resource Grant Using the Available CB Configuration

In a first embodiment, dynamic allocation of uplink resource blocks forcontention based access is achieved by using the Downlink PhysicalControl Channel (PDCCH). In FIG. 10 this is indicated as schedulinggrant SG. The Contention Based Radio Network Temporary Identifiers(CB-RNTI) are introduced to identify the contention based uplinkresources. UEs may listen for grants addressed to these CB-RNTIs inaddition to grants addressed to their dedicated C-RNTI. A benefit ofthis embodiment is that resources available for contention based accesscan quickly, e.g. on a per subframe basis, be allocated or revokeddepending on the need for other resources on the shared medium, such asresources dedicated to non-contended access. In this way, it can beachieved that scheduling of uplink CF transmissions is not affected anda static assignment of CB resources can be avoided.

In this embodiment, the transport format to be used in the CB resourceblocks is signaled on the PDCCH, as it is the case for CF transmission.To support different channel coding, resource block size, and/or packetsizes, several CB-RNTIs can be defined so that different uplinkparameters can be used in different CB resources, as indicated by a, band c in FIG. 10. Each UE can be assigned to listen to one or severalCB-RNTI, i.e. a UE assigned to resources a and b may select either ofthose while another UE may be assigned to resources b and c.

In an alternative embodiment, the uplink resource blocks for contentionbased access are signaled on the BCCH (Broadcast Control Channel). Abenefit of this embodiment is a low signaling overhead, since thecontention-based resources are semi-statically allocated.

In general, CB uplink grants may specify not only the resource blocksbut also transmission parameters to be used like multiplexing and codingscheme.

Allocation of CB Resources

There are different ways according to which the CB resources could bedivided. Below a few examples are listed.

-   -   Different CB resources can have different coding schemes. In        this way, a UE can select a CB resource dependent on the current        channel conditions, e.g. one with robust coding for the cell        edge or lighter coding for good downlink (DL) channel        conditions. If the UE is unaware of uplink propagation, DL        measured channel quality can be used as an estimate for the UL.    -   The UE may select uplink CB resources based on the amount of        data to be transmitted or a call type or a data priority, so        that small packets are transmitted on one resource and larger        packets on another resource or some CB resources could be        reserved for data of high priority or alarm calls. This can        avoid occupying a CB resource dimensioned for a large amount of        data with only a small packet and reduce the amount of padding.    -   UEs can be grouped, so that different groups access different CB        resources. For instance CB resources could be reserved gold,        silver and bronze users with different subscriptions to the        network operator.

Any of the above groupings can be combined with each other. Different CBgrants with different uplink transport formats could point to the sameuplink resource block(s). The UE selects the transport format that suitsits needs best, e.g. based on available data to send, link quality,desired block error rate, etc. Blind detection can be used in the eNB todetect the transmitted format.

In another embodiment no transport format signaling on the PDCCH isused. In this case, one or a few fixed transport formats are used forall contention based access. The transport formats are signaled inadvance by either broadcast on BCCH or by dedicated RRC signaling ate.g. call setup.

In a further embodiment, a UE is only allowed to transmit on CBresources if it does not have a dedicated CF grant.

Furthermore, the UE may only be allowed to use CB resources for alimited number of time intervals, e.g. subframes. For example it may usethe CB resources for at most one signaling Round Trip Time. Afterwardsthe eNodeB can start scheduling dedicated CF resources to the UE whichreduces the risk of collisions, and can improve data throughput by meansof link adaptation and HARQ (Hybrid Automatic Repeat Request) while notsuffering from additional signaling delays.

One problem with contention-based access is that the eNB has to map thereceived data to a certain UE. Thus, a unique UE identifier is includedin the MAC PDU. One option is to use the C-RNTI to identify the UE.Alternatively another UE identifier can be used, e.g. a TMSI. A thirdalternative is that the UE draws a random identity to be used in thecontention resolution. The identity (e.g. C-RNTI) can either be includedin the MAC-PDU using a MAC Control Element, or a new MAC-PDU formatcould be created for the CB resources, which includes the identity (e.g.C-RNTI) by default. A new MAC PDU format has the advantage that it canbe adapted specifically for CB transmissions. For notational simplicity,the UE specific identity based on which contention resolution isperformed is sometimes denoted “C-RNTI” in this text. However, a skilledperson is aware that other identities can be used for the same purpose.

EXAMPLE EMBODIMENT

Required parameters are broadcast in the cell, or the UE is configuredwith them via RRC. Possible parameters are listed below although furtherparameters could be specified:

-   -   Available CB-RNTIs    -   Access probability, e.g. in order to allow eNB to steer the load

In FIG. 10, three different types of CB resources are labeled a, b andc. A UE receiving data for uplink transmission from higher layers firstreads the PDCCH for an allocation of a resource block, i.e. a SchedulingGrant (SG) with the available CB-RNTIs. The SG is indicated by a wavehatching in the DL of FIG. 10. If the UE detects several CB-RNTIs, itcan select in which of the available CB resources to make thetransmission. This selection can be pre-specified, e.g. in aspecification, so that a simple selection algorithm can be used.Possible input parameters to the selection are listed below wherein thebit numbers indicate one option of the coding of information within thescheduling grants:

-   -   The CB scheduling grant on PDCCH        -   Hopping flag [1 bit] to indicate whether frequency hopping            is applied        -   Resource block allocation to indicate which RBs can be used            for PUSCH (Packet UL Shared Channel)        -   Modulation and coding scheme [5 bits]. If the full range is            not needed, some combinations could be used for other            purposes        -   New data indicator [1 bit] for use in soft combining        -   Phase rotation of UL reference signal [3 bits] to support            multi user MIMO for CF transmission. Phase rotation may also            be used to assign different phases for different CB grants,            to ease detection and decoding in eNB, for example when            different CB grants point to the same RBs.        -   Channel Status request flag [1 bit] to be used by the eNB to            request a Channel Status report        -   Uplink Index [2 bits] for Time Division Duplex        -   Transmit power control for PUSCH [2 bits] to control the UL            transmission power, e.g. to limit inter cell interference            level in case of high interference level at neighboring eNBs        -   Identity (RNTI) [16 bits] to indicate CB-RNTI, masked into            CRC calculation    -   DL channel quality    -   UL buffer size    -   UE power budget    -   Access probability (broadcasted by eNB)

Depending on the particular embodiment of the present method, theparameters are not mandatory and/or could be replaced by otherparameters. Using the above input parameters, the UE may determine inwhich of the available CB grants of a subframe, i.e. transmission timeinterval, to transmit.

The following pseudo code describes an option of a selection algorithm:

-   -   For each subframe;    -   Select CB grants with suitable modulation and coding scheme    -   Repeat for all applicable CB grants or until (dataBuffer=0)        -   Randomly select CB grant;        -   if RAND<access probability            -   Prepare data packet according to CB grant

Once the UL CB resources for transmission are selected from the SG, theUE performs physical layer (L1) processing of the data and transmits thedata in the corresponding UL resource block, marked by wave hatching inthe UL part of FIG. 10. Due to the time required for transmission andprocessing of data, the grant in DL and the corresponding UL resourceblock are shifted by 4 transmission time intervals. The UE maycontinuously read the PDCCH and thus be always aware of existing uplinkCB resources.

The MAC PDU can include a MAC Control Element with a unique identity(e.g. the C-RNTI) for user identification. If the UE has more data inthe buffer than it can transmit on the available CB resources, it caninclude a Buffer Status Report (BSR) to request uplink contention freeresources. The BSR is a request to the eNB to consider granting uplinkCF resources to the UE. A trigger for including a BSR could e.g. be thatthe buffered data in the UE exceeds an amount that can be transmittedduring a specific interval of time using the presently available CBresources. Alternatively, the UE can always include a BSR when sendingdata on CB resources and let the eNB decide whether to allocate UL CFresources. The BSR can for example be in the short or long format asdescribed in chapter 6.1.3.1 of 3GPP TS 36.321.

Due to the fact that the eNodeB cannot identify a UE performing CB datatransmission unless it successfully receives the transport block,another embodiment is that the UE also performs a state-of-the-artscheduling request (SR). In LTE the SR is done using a dedicatedresource on the PUCCH which occurs periodically but typically not ineach subframe as indicated in FIG. 10. Due to the single carrierproperty of the LTE uplink it is not possible to send the SR in parallelto any data transmission. Therefore, the UE may give priority to one ormore SR and perform CB data transmission in other subframes. If the eNBsuccessfully receives data on a CB resource close to an SR it mayreevaluate the necessity for further resource allocations in order toavoid unnecessary allocations.

A comparison of timelines for CB and CF transmission is shown in FIG.11. The tables show the durations of the individual signaling componentsin ms and correspond to the respective schematic signaling diagrams, theupper one corresponding to FIG. 2. The comparison shows that CBtransmission significantly reduces latency by avoiding the SR/SGhandshake before UL transmission. The figure omits the initiation periodfor CB transmission in which the eNodeB informs UE of available CB-RNTIseither by broadcast or dedicated signalling and in which the UE receivesthe CB-RNTIs and starts monitoring PDCCH for available CB grants.However, this initiation period does generally not add to thetransmission delay after reception of data for transmission as it can beperformed in advance. After the eNodeB has scheduled a CB grant on thePDCCH, the UE detects the CB grant, performs processing of the data tobe transmitted and transmits the data on the allocated resource of thePUSCH.

Transmission Acknowledgements

In contrast to contention free access with dedicated uplink grants, theeNodeB does not know which UE attempted to transmit on a CB resourceunless it successfully decodes the data. This is in particular the caseif a common redundancy check protects the content of a resource blockcomprising the UE identification so that any detected error may corruptthe UE identity. As a consequence, the eNodeB cannot send a dedicatednegative acknowledgement (NACK) to a particular UE. Also, a single-bitacknowledgement (ACK) being associated with the resource block and sentin response to a successful CB transmission is not appropriate in caseswhere multiple UEs attempted to transmit data.

Therefore, the successful reception of a CB uplink transmission ispositively acknowledged in an embodiment by signaling a UE specificidentifier in the downlink. This may be done by means of a downlink MACPDU including a MAC Control Element (CE) containing the UE's C-RNTI. TheMAC control element may be sent with a Scheduling Assignment on PDCCHusing e.g. the corresponding CB-RNTI or the UE-specific C-RNTI.Regardless of the option used, the purpose is to resolve ambiguitiesresulting from the contention such that only the UE that identifies itsunique identity in the downlink transmission assumes that thetransmission was successful. Another possibility is to send a ULScheduling Grant (SG) on the PDCCH with the UEs own C-RNTI. The SG couldalso be used to allocate UL CF resources to the UE at the same time. Ifno UL CF grant is to be given, this could be indicated to the UE byusing an invalid combination of information in the PDCCH SG.Alternatively, an indicator (e.g. 1 bit) could be included to indicatethe acknowledgement.

If the acknowledgement is sent with a fixed time offset to the uplinktransmission the UE can correlate the acknowledgement to the uplinktransmission. An alternative is to add a subframe offset field in theacknowledgement to indicate to the UE which subframe the acknowledgementcorresponds to, e.g. relative to the current subframe.

If the UE does not receive a dedicated positive feedback within aspecified time it may retransmit the data on a CB resource or on adedicated CF resource that has been scheduled in the meantime.Alternatively, if the UE identifies that it has lost contention, e.g. bythe fact that a CB resource utilized by the UE is acknowledged with anidentity not matching the identity of this UE, the UE can assume thatthe transmission was not successful. In such a case, the UE mayretransmit the unacknowledged transmission.

In an alternative embodiment, no MAC acknowledgements are transmittedfor CB uplink transmissions. Instead, one or more higher layers, e.g.RLC, RRC or potentially also IP-based protocols like TCP, control theretransmission of lost packets. This option can decrease the amount ofdownlink signaling at the expense of an increased packet delay forretransmitted packets due to the additional layers involved.

Soft Combining of Retransmissions

If transmission acknowledgements and retransmissions are supported,performing a retransmission after a fixed time will cause a newcollision if the loss of data was due to a collision. If retransmissionsare mainly caused by collision, retransmissions with soft combiningoffer only minor advantages. However, if retransmissions are mainly dueto other causes, soft combining may be advantageous.

In particular if the criterions listed below are met, the eNB couldopportunistically try to soft combine failed transmissions to generate acorrect version of the transmitted packet, similar to HARQ operation.

-   -   Retransmissions are performed with a fixed timing offset from        the previously failed transmission.    -   Retransmissions are performed in resource blocks corresponding        to the previously failed transmission, e.g. in a resource block        shifted by one round trip time. This requires that the eNB        repeats the scheduling of corresponding RBs for contention based        uplink transmission in the subframe where the retransmission is        expected. The eNB could indicate in the CB RNTI grant on the        PDCCH that it expects a retransmission. This is a signal to the        UE with failed transmission to retransmit, and at the same time        to other UEs not to start a new transmission in this CB        resource. By allocating a different CB-RNTI or using different        RBs, the eNB can also stop colliding UEs to perform a        retransmission after a fixed time, causing a new collision. This        requires that the eNB has some means of detecting the collision,        e.g. by letting UEs use different reference symbols.    -   Retransmissions of the same packet are performed with the same        modification of the reference symbol. This enables the eNB to        identify transmissions from the same UE so that combining two        failed transmissions could yield a correct version of the        packet. Since there are only a limited number of reference        symbol offsets, there is a possibility that another UE transmits        with the same reference symbol modification in the same resource        block.

In general, the method of UE retransmission may be specified for thecase that no response is received from the eNB or a response indicatingthat the eNB detected the transmission but did not successfully decodethe data. For example the UE(s) could retransmit according to aspecified pattern, which facilitates soft-combining, or if a collisionis possible, the contending UEs may back off with different, e.g. randomtime- or frequency offsets like in an Aloha scheme.

In an embodiment, if the UE detects the same CB-RNTI scheduling the sameRBs and indicating a retransmission, it should retransmit in these RBs.The indication of a retransmission may be an indication to other userequipments not to initiate new CB transmissions in the same resources.If the UE does neither receive an ACK nor detect the same CB-RNTIscheduling the same RBs, it may generate a local NACK (Negative ACK) tothe own RLC layer, i.e. an indication within the protocol stack, and letRLC control the retransmission. A random backoff time may avoidsuccessive collision.

RLC Configuration

If embodiments of the proposed methods are implemented in the MAC layerof LTE user equipment and eNBs, changes to the default configuration ofthe RLC layer above the MAC layer can enhance the advantages. For theuplink, the following RLC configuration embodiments are implementationoptions for the RLC receiver, e.g. in the eNB, which require nostandardization or RRC signaling.

In LTE systems, data unit reordering due to HARQ retransmissions iscorrected by the RLC layer. A reordering timer is used to wait forpotentially successful retransmissions in case a gap in received RLCsequence numbers is detected. The transmission of a status report torequest an RLC retransmission is delayed until the timer expires, andcancelled if the retransmission was successful in the mean time. Withcontention based uplink, the reordering timer is only needed if MAClevel retransmissions are performed and soft combining is used. Else anygap is due to loss of data.

In case MAC level retransmissions are not supported and no MACacknowledgement is received, a local NACK may be passed in the UE fromthe MAC layer to the RLC layer which triggers an RLC retransmission ofthe lost PDU. As no variance in MAC transmission delay occurs, thereordering timer in the RLC receiver is not needed.

The RLC layer may also be made aware whether MAC layer retransmission issupported or not. This may change for an ongoing radio link, dependingon whether uplink contention based or contention free transmissionresources are used. This could be realized by an indication from MAC toRLC indicating for each RLC PDU whether it was sent as CF or CBtransmission.

RLC polling for status reports can also be optimized for contentionbased transmissions. The importance of the RLC polling mechanism isreduced if retransmissions are mostly triggered by local NACKs due tomissing MAC ACK. Accordingly, the poll timer may be reduced to a puresafeguard mechanism to prevent protocol stall, i.e. the value of thetimer could be increased or the timer be switched off. Polling on emptybuffer is then sufficient and could be triggered by checking the bufferstatus.

Changing the UE RLC configuration according to CB and CF transmissionsmay not be advantageous in all cases if it requires RRC signaling.Alternatively, the RLC polling and status reporting configuration maythus be kept the same for CB and CF transmissions.

Link Adaptation

In LTE Release 8, the eNB performs link adaptation and transport formatselection. For contention based uplink transmission a new approach isrequired. Two embodiments which may be combined are presented in thefollowing.

In a first option, a number of Transport Formats (TF) is defined, e.g.by the eNB, and mapped to different CB-RNTIs. The TF can for examplecomprise a Modulation and Coding Schemes (MCS). The UE selects anappropriate CB-RNTI e.g. according to the amount of data to transmit,measured DL path loss and/or uplink power budget. More than one CB-RNTImay point to the same RB. In this way the UE can select different MCSand TF combinations for the same RB depending on the CB-RNTI. Blinddetection can be used in the eNB to detect the transmitted format amongthe possible options. Alternatively, it may be defined that a UE isallowed to select among a, potentially limited, set of transport formatsin response to a single CB-RNTI allocation. To simplify decoding,different uplink reference symbol phases may be dedicated to differentoverlapping CB-RNTIs. This can improve the detection of the usedCB-RNTIs in the eNB.

In a second option, a variable number of resource blocks signals theused transport format from the UE to the eNB. In this option, the eNBsignals which RBs are available for contention based uplink transmissionusing one or several CB-RNTIs. The coding rate for these RB may befixed, and the UE selects the number of RBs to use according to theamount of data to transmit, DL path loss and uplink power budget. Thus,the TF depends on the number of RBs used and the eNB can determine theused TF by detecting how many RBs are received.

In case of collisions, the eNB may erroneously try to decode detectedRBs from different user equipments into one data packet, i.e. TransportBlock. In this case decoding may fail and both transmissions are lost.This can also be the case for two UEs transmitting over adjacent RBs.This could be avoided by using different offset or modification of thereference symbols.

The number of selected RBs may be smaller than the number resourceblocks allocated for CB transmission, e.g. 10 free RBs in an uplinksubframe, and the UE selecting to transmit in 4 of them. In this casedifferent options exist for the UE to select the used RBs, e.g. randomselection, or starting from an edge of a range of resource blocks.

Reference Signals

Reference signals, sometimes also denoted as reference symbols, enablecoherent demodulation of physical channels. In LTE, uplink referencesignals are time-multiplexed with the data for transmission andtransmitted in the fourth symbol of each uplink slot, a subframe in LTEcomprising 2 slots. The bandwidth is the same as the ongoing ULtransmission, i.e. a reference signal spans the same number of resourceblocks if the UL transmission of a user is performed on more than oneadjacent resource block. The reference signal sequences are ordered intogroups, so that each group contains one sequence for each possibleresource allocation. In LTE, there are 30 different groups of referencesignal sequences, and there is one group per cell. Thus, for a givenbandwidth of a resource allocation in a cell, the same reference signalis used.

Modification of the reference signals by phase rotation can be used todifferentiate between transmissions in the same resource block, forexample to separate transmissions of several users in a resource block.This is used e.g. for PUCCH transmission. In total, 12 phase rotationsare available, but not all can be used if orthogonality is to bemaintained between different resource blocks. For PUCCH, typically 6rotations are used. Thus the number of possible modifications of thereference signals is generally limited and the use of other proceduresof user differentiation may be required in addition.

Phase rotation of reference signal could accordingly be used in thereceiver of a CB RB, e.g. the eNB, to detect if different UEs are tryingto access the radio network simultaneously or consecutively. If theoption of variable RB numbers is used to for link adaptation, thereceiver can thus detect that transmissions in RBs come from differentusers, e.g. from 2 users transmitting with 4 RBs each over 8 consecutiveRBs.

Phase rotation of reference signal can also be used to detecttransmission collisions. The results of the collision detection can beused by the CB resource allocation algorithm. In case collisions becomefrequent, the eNB can refrain from CB allocation and rather allocate CFresources. Reducing CB resources to zero in a subframe may be used tocause UEs to send a Scheduling Request, rather than a CB transmission.

In a further embodiment, phase rotation or phase shift of referencesignals could also be used to detect which CB-RNTI was used if there aremultiple overlapping grants for the same physical resource blocks. TheUE would then apply the modification of the reference signal independence on the CB-RNTI selected for transmission.

Support for Unsynchronized User Equipment

To improve the transmission latency also for unsynchronized userequipment, the contention based scheme can be extended to unsynchronizedUEs in an embodiment. For unsynchronized UEs, guard times avoidinterference towards adjacent subframes. Interference may result if timemisalignment causes an unsynchronized UE to transmit such that thereception of this transmission in the eNB overlaps two subsequentsubframes. To avoid interference between transmissions due to overlap itis an option to avoid allocating resource blocks for new transmissionsin every second subframe.

For unsynchronized UEs, a preamble is preferably sent before or at thebeginning of a transmission so that the eNB can detect the timing offsetof the UE transmission. Optionally, a first subframe contains thepreamble transmission, and a CB RB of a subsequent subframe contains atleast a part of the for data transmission. The first and second subframemay be separated in time, or they may be adjacent.

If the preamble is sent prior to the data transmission the radio networkcan send time alignment information according to the detected offset inresponse. In case the first and second subframes are separated in time,there may be a timing-adjustment performed between the subframes, suchthat timing alignment is achieved based on the preamble transmissionprior to the transmission of the second subframe containing data. Suchtime-alignment could be applied using a response message from the eNBbetween the aforementioned first and second subframes in line with theLTE release 8 procedures of contention free uplink transmission.

In order to reduce latency, uplink data transmission is started beforereceiving an SG and RBs for contention free transmission by using thecontention based transmission as described before for synchronizedusers. RBs for contention based transmission are, e.g., signaled usingCB-RNTIs on PDCCH. The CB-RNTIs can indicate whether the allocation isfor use by synchronized or unsynchronized UEs, e.g. if different numberranges are defined for synchronized and unsynchronized UEs.Alternatively, the same CB-RNTIs can be used for both synchronized andunsynchronized UEs.

An example is shown in FIG. 12. Here, the UE receives new data in abuffer in step or TTI 1201. After processing the data it initiates theUL transmission a few subframes later in step 1202 with a preamble onPRACH (Physical Random Access Channel). As mentioned the selectedpreamble may indicate whether it corresponds to a CB or a CFtransmission. The UE then starts the UL data transmission in step 1203,i.e. before an SG is received, with the same timing in the RBs reservedfor CB transmission (wave-shaped hatching). Note that the transmissionin the example is not precisely aligned with the start of the subframedue to the missing synchronization. An offset between the preambletransmission and the data transmission, one subframe in the presentexample, may simplify it for the eNB to adjust the receiver. During theongoing transmission, the UE receives a scheduling grant with timealignment information in step 1204. After processing this information,the UE can begin synchronized transmission in step 1205, preferably inCF resources.

As mentioned, the preamble space can be divided between contention freeand contention based access, to indicate to the eNB which kind of accessthe UE makes. There may be an association between one or a set ofpreambles and a CB resource that may be coded in the specifications,controlled by RRC signaling on BCCH or DCCH (Dedicated Control Channel),or the control may be provided on PDCCH. This could simplify thereceiver due to the information in which RBs to expect the transmissionbased on the received preamble.

In view of the short subframe duration, transmissions may span severalsubframes to increase efficiency. This is also illustrated in FIGS. 12and 13 where CB transmission takes place in 5 or 6 subsequent subframesrespectively. Continuous CB transmission could be allowed as long as thesame RB allocations are signaled in subsequent subframes for CB accesswith the same format on PDCCH. If the CB configuration changes betweensubframes, a new PRACH transmission is again required. Alternatively,the UE can await a Scheduling Grant for contention free resources. Ifthe UE receives the grant, transmission using CB grants is preferablystopped.

A busy flag could be used to indicate to other UEs that a transmissionis ongoing in a CB resource to reduce collision probability. The eNBcould indicate this on PDCCH, but because of the offset of 4 subframesbetween sending and decoding of the information, the flag would onlysecure the last few subframes of a CB transmission.

The resources allocated for the preamble transmission may also bedifferent from the PRACH. In an embodiment of the invention, theresource blocks for preamble transmission are accordingly signaled byspecific Preamble Transmission (PT)-RNTI(s). This is illustrated in FIG.13 in which the preamble is sent in resource blocks signaled byPT-RNTIs. Here the UE first receives data for transmission in step 1301,detects a preamble grant in step 1302 on the downlink control channeland processes the included information. The UE then sends the randomaccess preamble on the defined resource block in step 1303. Thesubsequent steps 1304-1306 of the transmission correspond to those inFIG. 12. The PT-RNTIs used can be pre-specified, e.g. defined in astandard, broadcasted on BCCH or configured on DCCH.

Allowing preamble transmissions outside the PRACH can significantlyreduce the latency compared to CF transmission as the latency for CFtransmission is to a large part due to the average waiting delay for aPRACH period. For the contention free case, a PUCCH cycle of e.g. 10 mscan be assumed. While the cycle period could in principle be decreased,this would result in a capacity loss as the resources reserved for PRACHcan not be used for PUSCH transmission. For the contention based case,the resources for preamble transmission can in contrast be allocated onsubframe level without blocking the resources for data transmission. Atlow system load, the eNB can assign resources for preamble transmissionin each subframe, without degrading PUSCH capacity at high load, inparticular if an assignment of CB resources is omitted at high loadlevels.

Support for Idle Mode UEs

It is also possible to implement the proposed method for UEs in modeRRC_IDLE, i.e. when the UE has not yet performed a connection set-up tothe eNB during which it was associated with a C-RNTI that uniquelyidentifies it or when the association was removed again. In the modeRRC_IDLE, the UE consequently has no context or C-RNTI in the LTE radioaccess network and contention resolution has to be performed bydifferent means because there is no unique identity of the UE known bythe eNB. In an embodiment for RRC_IDLE mode, the UE may identify itselfusing e.g. a core network identity such as the TMSI. Alternatively, theUE may transmit a random identity providing sufficient uniqueness, suchthat contention resolution can be resolved using the embodimentsdescribed.

The UE sends data for transmission and includes the aforementionedidentity in the first transmission on the CB resource. Upon successfulreception of the transmission, the eNB may be configured to transmit thesame identity in a subsequent downlink transmission back to the UE. A UEdetecting its identity in the downlink transmission can assume that theCB transmission was successful. A UE can assume that the UL transmissionwas unsuccessful if it does not detect its identity in the associateddownlink transmission, either due to lack of any successful reception offeedback from the eNB or due to reception of a different UE identity.

Contention resolution using a higher layer identity, e.g. the TMSI, issupported in MAC through the use the 6 byte UE Contention ResolutionIdentity MAC Control Element defined in chapter 6.1.3.4 of specification36.321. In the response to a CB transmission, in which the UE is notidentified by a C-RNTI, the eNB may allocate a C-RNTI to the UE, andtransmit the C-RNTI to the UE in the downlink response message. A UEthat is lacking a C-RNTI may thus receive a new C-RNTI in the responsemessage indicating that the CB access was successful.

FURTHER EMBODIMENT

In contrast to the previous example, the UE in the embodiment describedbelow is in a mode RRC_CONNECTED, meaning that the UE has a connectionto the eNB including a C-RNTI that uniquely identifies the UE. Aflowchart of the UE operation is shown in FIG. 14.

Required parameters for uplink contention based transmission can bebroadcast in the cell or the UE is configured with them, e.g. via RRC,in step 1402. The UE then enters a waiting state 1404 in which it checksthe occurrence of particular events, e.g. the detection of one or moreuplink grant in step 1406. For this purpose, the UE can monitor the DLcontrol channel for at least one CB-RNTI it is allowed to use and theown C-RNTI. The UE determines in step 1408 if it has data fortransmission in a buffer. If this is not the case it returns to waitingstate 1404. If data for transmission is available the further processingdepends on the kind of grant as indicated by the check in step 1410.

In case the detected grants comprises one or more CB grants and inparticular if it consists only of a CB grant, the user equipment selectsa suitable CB resource associated with the CB-RNTI that would fulfillits needs for transmission in step 1412.

Before transmitting a MAC PDU in one of the available UL CB resourceblocks, the UE compares in step 1414 the amount of data with the datarate associated with the CB allocation divided by the round trip time,i.e. the amount of data that can be transmitted during one round triptime on the selected CB resources and it determines whether the CBallocation is sufficient for transmission of the data in the buffer. Ifthe allocation is sufficient, the UE creates a MAC PDU comprising theC-RNTI in step 1416. The MAC PDU can include for example a MAC ControlElement (CE) with the C-RNTI for user identification, e.g. the MAC CE asspecified in specification 36.321 which comprises 2 bytes. Then the UEprocesses the PDU for transmission, transmits the information of the MACPDU on the selected CB resource block(s) in step 1418, and returns tothe waiting state 1404.

If the UE determines in step 1414 that it has more data in the buffer,it again creates a MAC PDU in step 1420 and transmits it in step 1418 asdescribed before. However, the MAC PDU created in step 1420 canadditionally include a Buffer Status Report (BSR) to request uplinkcontention free resources. In other words, the BSR is a request to theeNB to consider granting uplink CF resources to the UE. As analternative to the check in step 1414, the UE can also always includethe BSR, and let the eNB decide whether to allocate UL CF resources.

Upon correct decoding of an UL CB transmission, the eNB acknowledges thetransmission by sending a grant with the UE specific C-RNTI on the PDCCHwith a fixed time offset to the UL MAC PDU transmission. If only onetransport block is transmitted per transmission time interval, the UEcan correlate the ACK to the uplink transmission without the need for aUL MAC sequence number. Besides acknowledging the uplink transmission,the same message can also be used to grant CF resources to the UE. If noUL CF grant is given, this could be indicated to the UE by using aninvalid combination of information in the PDCCH grant. Alternatively, anadditional bit could be added to indicate whether the grant is also anACK for CB transmission. The UE determines in step 1422 after one roundtrip time has elapsed whether it received the ACK, e.g. whether theevent of expiry of a corresponding timer occurred. For MAC PDUs that arenot acknowledged by the eNB, the UE may generate a local negativeacknowledgement to the RLC layer in step 1424 so that the RLC layer caninitiate a retransmission and provide the RLC retransmission as new datafor transmission in the buffer. The retransmission can occur on eitherthe CB resource or a CF resource if such has been granted by the eNB.

The grant in the acknowledgement or another uplink grant can alsotrigger again the transmission sequence via step 1406. If the UE hasstill data for transmission as determined in step 1408 it can performfurther data transmission as described before. The UE can be allowed tocontinue UL transmission on one CB resource per subframe for one roundtrip time. If the uplink grant comprises a CF grant as determined instep 1426, further data transmission can continue on granted CFresources as indicated by step 1428. Depending on the implementation, itis possible that check 1426 for CF grants is in contrast to FIG. 14executed prior to consideration of CB grants so that CF resources areused if those are available.

FIG. 15 shows contention based transmission with acknowledgementsaccording to the embodiment. Incoming uplink data is detected in the UEand the transmission is started in transmission time interval (TTI)1502. The figure shows how the Scheduling Grants (SG) are transmitted inthe DL with a constant offset of 4 subframes to the uplink CBtransmissions. The offset is due to the delay for processing andtransmitting of the data and a fixed offset uniquely identifies theassociated time intervals in UL and DL. Arrows indicate how the SGscorrespond to the CB transmissions, i.e. which SG acknowledges whichtransmission and which CF resource is reserved by the SG. A missing SGcan trigger a local negative acknowledgement within the UE to the RLClayer, which initiates the retransmission in a CF resource. This isshown for the CB transmission sent in TTI 1504 which is lost due atransmission error. It should be noted that the UE can still receive aCF uplink grant for TTI 1506, e.g. if a BSR in a previously successfultransmission indicated the need for the allocation.

In general, the proposed method allows reducing the latency for uplinktransmission by allowing the UEs to perform uplink transmission withoutinitial scheduling request and/or grant signaling. The latency isespecially reduced for the case where a UE does not have scheduleduplink resource. The method enables also the transition from a dormantstate to an active transmission, which takes no more than 10 ms.

In this way, also the amount of control signaling can be reduced ascontention based transmission does not include transmission ofScheduling Requests. On the other hand, DL signaling may increase, asPDCCH Scheduling Grants schedule the UL RBs for CB access. However,these CB Scheduling Grants are preferably only transmitted in periods oflow load so that the additional PDCCH load should not be a problem. Inparticular for small amounts of data transmission on CB resources may bemore efficient than CF transmission with scheduling.

A UE can provide the BSR already in the first CB transmission. Thismeans that the eNB can schedule the UE based in buffer status directlyfrom the start. In contrast, for contention free transmission the eNBinitially schedules the UE blindly as the Scheduling Request does notinclude buffer status information. Accordingly, the initial CFallocations can already be adapted to the UE requirements.

The above embodiments admirably achieve the objects of the invention.However, it will be appreciated that departures can be made by thoseskilled in the art without departing from the scope of the inventionwhich is limited only by the claims.

1-32. (canceled)
 33. A method implemented by a control device of a radionetwork for allocating resource blocks to user equipments that areconfigured to transmit data using those resource blocks, the methodcomprising: allocating one or more resource blocks to user equipmentsfor the user equipments to transmit a preamble associated withtransmission of said data to the control device, wherein the one or moreresource blocks allocated for transmission of a preamble are differentfrom a physical random access channel; allocating one or more resourceblocks either to a single one of the user equipments for contention freetransmission of said data or to multiple ones of the user equipments forcontention based transmission of said data, wherein at least one of theresource blocks that is not allocated for contention free transmissionis allocated to a first plurality of the user equipments for contentionbased transmission; and signaling the allocations to the userequipments.
 34. The method according to claim 33, wherein signalling theallocations for transmitting a preamble comprises signaling a preambletransmission radio network temporary identifier.
 35. The methodaccording to claim 33, wherein the signaling includes an indication asto whether an allocation is for use by synchronized or unsynchronizeduser equipments.
 36. The method according to claim 33, comprisingallocating one or more resource blocks to at least one single userequipment for contention free use.
 37. The method according to claim 33,wherein signalling an allocation comprises signalling, on a controlchannel or on a broadcast channel, a specific identifier that identifiesthe signaled allocation.
 38. The method according to claim 33, whereinthe first plurality of the user equipments comprises a pre-specifiedgroup of the user equipments.
 39. The method according to claim 33,wherein the resource blocks correspond to time intervals and whereinconsecutive allocations to the first plurality of the user equipmentsare separated by a time interval.
 40. The method according to claim 33,further comprising determining a traffic load for the radio network andwherein allocating one or more resource blocks for transmission of saiddata depends on the determined load.
 41. A method implemented by a userequipment for transmitting data to a radio network using resource blocksallocated to the user equipment by the radio network, the methodcomprising: obtaining data for transmission, receiving from the radionetwork an allocation of one or more resource blocks for the userequipment to transmit a preamble associated with transmission of saiddata, wherein the one or more resource blocks allocated for transmittingthe preamble are different from a physical random access channel;transmitting the preamble to the radio network using the one or moreresource blocks allocated for transmitting the preamble; receiving fromthe radio network an allocation of at least one resource block eithersolely to the user equipment for contention free transmission of saiddata or to a plurality of user equipments, which includes said userequipment, for contention based transmission of said data; processingthe allocation received for transmission of said data to determine theat least one resource block and to determine that the at least oneresource block has been allocated to a plurality of user equipmentswhich includes said user equipment; and transmitting at least a firstpart of the data using said at least one determined resource block. 42.The method according to claim 41, wherein receiving at least oneallocation of one or more resource blocks for the user equipment totransmit a preamble comprises receiving a preamble transmission radionetwork temporary identifier.
 43. The method according to claim 41,wherein receiving at least one allocation for transmission of said datacomprises receiving, on a control channel or on a broadcast channel, aspecific identifier that identifies the received allocation.
 44. Themethod according to claim 41, wherein said transmitting comprisesincluding an identifier into the transmission that identifies the userequipment to the radio network.
 45. The method according to claim 41,further comprising sending, outside the at least one resource block, ascheduling request for an allocation of a resource block dedicated forcontention free transmission by the user equipment.
 46. The methodaccording to claim 41, wherein transmitting the preamble comprisestransmitting the preamble for time alignment in association with the atleast one resource block.
 47. A control device of a radio networkconfigured to allocate resource blocks to user equipments fortransmission of data using those resource blocks, wherein the controldevice comprises: a processor configured to: allocate one or moreresource blocks to user equipments for the user equipments to transmit apreamble associated with transmission of said data to the controldevice, wherein the one or more resource blocks allocated fortransmission of a preamble are different from a physical random accesschannel; allocate one or more resource blocks either to a single one ofthe user equipments for contention free transmission of said data or tomultiple ones of the user equipments for contention based transmissionof said data, wherein at least one of the resource blocks that is notallocated for contention free transmission is allocated to a firstplurality of the user equipments for contention based transmission; anda transmitter configured to signal the allocations to the userequipments.
 48. A user equipment configured to transmit data to a radionetwork using resource blocks allocated to the user equipment by theradio network, the user equipment comprising: a buffer for storing datafor transmission, a receiver configured to receive from the radionetwork an allocation of one or more resource blocks for the userequipment to transmit a preamble associated with transmission of saiddata, wherein the one or more resource blocks allocated for transmittingthe preamble are different from a physical random access channel; atransmitter configured to transmit the preamble to the radio networkusing the one or more resource blocks allocated for transmitting thepreamble; wherein the receiver is further configured to receive from theradio network an allocation of at least one resource block either solelyto the user equipment for contention free transmission of said data orto a plurality of user equipments, which includes said user equipment,for contention based transmission of said data; a processor configuredto process the allocation received for transmission of said data todetermine the at least one resource block and to determine that the atleast one resource block has been allocated to a plurality of userequipments which includes said user equipment; and a controllerconfigured to select the at least one resource block responsive to astatus of the buffer and the allocation determined by the processor, andwherein the transmitter is configured to transmit at least a first partof the data using said at least one of resource block selected by thecontroller.